The present invention relates to the field of micro mechanical or micro electromechanical liquid ejection devices. The present invention will be described herein with reference to Micro Electro Mechanical Inkjet technology. However, it will be appreciated that the invention does have broader applications to other micro mechanical or micro electromechanical devices, eg. micro electromechanical pumps.
Micro mechanical and micro electromechanical devices are becoming increasingly popular and normally involve the creation of devices on the micrometer (micron) scale utilizing semi-conductor fabrication techniques. For a recent review on micro-mechanical devices, reference is made to the article xe2x80x9cThe Broad Sweep of Integrated Micro Systemsxe2x80x9d by S. Tom Pieraux and Paul J. McWhorter published December 1998 in IEEE Spectrum at pages 24 to 33.
One form of micro electromechanical devices in popular use is an ink jet printing devices in which ink is ejected from an ink ejection nozzle chamber. Many forms of ink jet devices are known.
Many different techniques on ink jet printing and associated devices have been invented. For a survey of the field, reference is made to an article by J Moore, xe2x80x9cNon-Impact Printing: Introduction and Historical Perspectivexe2x80x9d, Output Hard Copy Devices, Editors R Dubeck and S Sherr, pages 207 to 220 (1988).
Recently, a new form of ink jet printing has been developed by the present applicant, which is referred to as Micro Electro Mechanical Inkjet (MEMJET) technology. In one form of the MEMJET technology, ink is ejected from an ink ejection nozzle chamber utilising an electro mechanical actuator connected to a paddle or plunger which moves towards the ejection nozzle of the chamber for ejection of drops of ink from the ejection nozzle chamber.
The present invention concerns improvements to liquid ejection devices for use in the MEMJET technology or other micro mechanical or micro electro-mechanical devices.
In accordance with the present invention, there is provided a liquid ejection device comprising: a nozzle chamber having a first aperture in one wall thereof for the ejection of liquid and a second aperture in a wall thereof through which an actuator arm extends, the actuator arm being attached to a substrate located outside the nozzle chamber and being connected to a paddle inside the nozzle chamber, the paddle being operable by way of the actuator arm to eject the liquid through the first aperture; the system further comprising a first raised rim formed around the second aperture, the first raised rim being arranged in a manner such that, during operation of the actuator arm, a liquid meniscus is formed along an outer surface of the liquid between the first raised rim and the actuator arm.
Accordingly, spreading of the liquid outside of the nozzle chamber through the second aperture may be prevented.
The actuator preferably can include a planar portion adjacent the first raised rim, the planar portion being generally parallel to and spaced apart from the substrate.
The first raised rim preferably can include an edge portion substantially parallel to the planar portion.
The first raised rim may comprise a raised lip.
The device may further comprise a second raised rim formed on the actuator arm adjacent the first raised rim formed around the second aperture. In this embodiment, the second raised rim may assist in the prevention of spreading of the liquid outside of the nozzle chamber through the second aperture.
The first raised rim can be formed from deposition of a layer which also forms a portion of the actuator arm.
At least on of the first and second raised rims can be formed from titanium nitride.
Adjacent the first raised rim there is preferably formed a pit to assist in reducing wicking.